A Manchester encoder in a transmitter is shown in FIG. 1, the encoder encodes “1” or “0” of the original data into “01” or “10”, and then transmits the same. In the descriptions of the present invention, the original data “1” is encoded into “01”, the original data “0” is encoded into “10”, whereas a reverse condition is also possible depending upon the system.
The Manchester encoder shown in FIG. 1 encodes the original data “110100 . . . ” into “010110011010” and then transmits the same.
A Manchester decoder in a receiver is shown in FIG. 2, which executes a decoding process, in which “1” or “0” data is extracted from samples “01” or “10” after a glitch is eliminated by removing noises from the received data, and a phase of a reference clock is calibrated. That is, two times of sampling are executed, and the result values are decoded.
The received encoded data “010110011010 . . . ” is decoded into the original data “110100 . . . ”.
However, it is difficult for the Manchester decoder to extract data when the received signals are severely distorted due to a condition of poor channel or the like, and the decoding performance of the decoder is degraded accordingly.
FIG. 3 illustrates distortion of an input signal a conventional decoder. As shown in FIG. 3a, the received normal data “010110011010 . . . ” is likely to be distorted as shown in FIG. 3b and inputted into the Manchester decoder.
As shown in FIG. 2, data “1” or “0” are extracted from “01” or “10” by sampling the original data two times. Therefore, a decoding error occurs when the signal is distorted as shown in FIG. 3.